INTEGRATIVE AND SELF-REPLICATING LC VECTORS AND THEIR TRANSACTIVATIONCAPACITY IN MAIZE CALLUS PROTOPLASTS

The regulatory Lc gene is a member of the R gene family of maize which amongst other transcriptional activators controls anthocyanin biosynt hetic genes. The availability of R locus mutants which lack anthocyani n production in all tissues offers the possibility of studying cell li neage by introducing a chimeric Lc gene into defined cells and followi ng cell autonomous anthocyanin production. For this purpose integrativ e and self-replicating Lc vectors were constructed. Integrative expres sion vectors contained the 2.4 kbp Lc cDNA with the entire 5' leader f used to the constitutive cauliflower mosaic virus 35S promoter with an d without the maize alcohol dehydrogenase 1 intron 1 or to the mesophy ll specific phosphoenolpyruvate carboxylase promoter of maize. To enha nce expression and to circumvent the necessity of stable integration, extrachromosomally replicating and expressing wheat dwarf virus-Lc con structions were also designed. Both categories of expression vectors w ere tested in embryogenic callus-derived protoplasts of maize and were found to transactivate anthocyanin biosynthesis. Southern blot analys is indicated that the wheat dwarf virus-lc constructions were replicat ing.